scholarly journals Long-Term Changes in Hydrological Regime of the Lakes Usma, Burtnieks and Rāzna

2012 ◽  
Vol 66 (6) ◽  
pp. 261-270
Author(s):  
Elga Apsīte ◽  
Mārtiņš Kriķītis ◽  
Inese Latkovska ◽  
Andrejs Zubaničs
Keyword(s):  
Water Level ◽  
Global Climate ◽  
Hydrological Regime ◽  
Positive Trend ◽  
Global Climate Warming ◽  
Regional Features ◽  
Natural Factors ◽  
Ice Regime ◽  
The Impact

Changes in the hydrological regime of the lakes of Latvia have been caused by several natural and human factors. This publication summarises the results of research on the long-term and seasonal changes in the water level, and thermal and ice regimes of the three biggest lakes of Latvia (Usma, Burtnieks, and Râzna) and their regional features in the period from 1926 to 2002. The levels of the lakes Usma and Râzna have been controlled, but it can be considered that changes of the water level in Lake Burtnieks have been due to the impact of natural factors during the period from 1947 to 2002. Global climate warming has caused considerable changes in the hydrological regime of the lakes during the last decades, as the water level and temperature have increased and the number of days with ice cover and the thickness of ice have decreased. A positive trend in the freezing data and statistically reliable negative trend for the ice break-up date were observed for all the lakes. Lake Usma is located in the western part of Latvia, therefore, its hydrological regime, in particular, the thermal and ice regime, differs from those of lakes Burtnieks and Râzna which are located in the northern and eastern part of Latvia, respectively.

Long-term changes in hydrological regime of the lakes in Latvia

2013 ◽  
Vol 45 (3) ◽  
pp. 308-321 ◽  
Author(s):  
Elga Apsīte ◽  
Didzis Elferts ◽  
Andrejs Zubaničs ◽  
Inese Latkovska
Keyword(s):  
Surface Water ◽  
Water Level ◽  
Global Climate ◽  
Hydrological Regime ◽  
Positive Trend ◽  
Surface Water Temperature ◽  
Global Climate Warming ◽  
Long Term Changes ◽  
Ice Regime

Changes in the hydrological regime of the lakes of Latvia depend on natural and anthropogenic causes. This publication summarises the results of the research on the long-term changes in the water level, thermal and ice regimes in the seven largest lakes of Latvia: Liepājas, Usma, Ķīšezers, Burtnieks, Rāzna, Sventes and Lielais Ludzas, and their regional specifics from 1926 to 2002. For most of the studied lakes, the water level has been regulated, except for the lakes Liepājas, Burtnieks and Ķīšezers. Global climate warming has caused considerable changes in the hydrological regime of the lakes during the last decades and the surface water temperature has increased. At the same time, the number of days with ice cover and the thickness of ice have decreased. A positive trend in the freezing date and a statistically significant negative trend for the ice break-up date was found for all lakes. The lakes Liepājas and Usma are located in the western part and Lake Kīšezers in the central part, therefore their hydrological regime, in particular, the thermal and ice regime, differs from the lakes Burtnieks, Rāznas, Sventes and Lielais Ludzas which are located in the northern and south-eastern part of Latvia.

scholarly journals Assessing Stream-Aquifer Connectivity in a Coastal California Watershed

Water ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 416
Author(s):  
Bwalya Malama ◽  
Devin Pritchard-Peterson ◽  
John J. Jasbinsek ◽  
Christopher Surfleet
Keyword(s):  
Time Series ◽  
Spectral Analysis ◽  
Water Level ◽  
Time Series Data ◽  
Series Data ◽  
Low Permeability ◽  
Pumping Tests ◽  
Stream Flows ◽  
The Impact

We report the results of field and laboratory investigations of stream-aquifer interactions in a watershed along the California coast to assess the impact of groundwater pumping for irrigation on stream flows. The methods used include subsurface sediment sampling using direct-push drilling, laboratory permeability and particle size analyses of sediment, piezometer installation and instrumentation, stream discharge and stage monitoring, pumping tests for aquifer characterization, resistivity surveys, and long-term passive monitoring of stream stage and groundwater levels. Spectral analysis of long-term water level data was used to assess correlation between stream and groundwater level time series data. The investigations revealed the presence of a thin low permeability silt-clay aquitard unit between the main aquifer and the stream. This suggested a three layer conceptual model of the subsurface comprising unconfined and confined aquifers separated by an aquitard layer. This was broadly confirmed by resistivity surveys and pumping tests, the latter of which indicated the occurrence of leakage across the aquitard. The aquitard was determined to be 2–3 orders of magnitude less permeable than the aquifer, which is indicative of weak stream-aquifer connectivity and was confirmed by spectral analysis of stream-aquifer water level time series. The results illustrate the importance of site-specific investigations and suggest that even in systems where the stream is not in direct hydraulic contact with the producing aquifer, long-term stream depletion can occur due to leakage across low permeability units. This has implications for management of stream flows, groundwater abstraction, and water resources management during prolonged periods of drought.

Comparison of mayfly (Ephemeroptera) taxocenes of permanent and intermittent Central European small streams via species traits

Biologia ◽  
2010 ◽  
Vol 65 (4) ◽  
Author(s):  
Pavla Řezníčková ◽  
Tomáš Soldán ◽  
Petr Pařil ◽  
Světlana Zahrádková
Keyword(s):  
Global Climate ◽  
Extreme Temperature ◽  
Oxygen Demand ◽  
Hydrological Regime ◽  
Species Traits ◽  
Individual Species ◽  
Biological Traits ◽  
Small Streams ◽  
High Oxygen Demand ◽  
The Impact

AbstractThe recurrent drying out of small streams in past decades has shown an urgent need to pay attention to the impact of global climate change. The objectives of this study were to describe the effect of drying out on the composition of the mayfly taxocene and evaluate the relevance of individual species traits for survival of mayflies to drying out. The mayfly taxocenes of two model localities, one at an intermittent and one at a permanent brook, were investigated in 2002, 2003 and 2005. Compared with the permanent stream, the taxocene of the intermittent stream was short of nine species, foremost rheobionts and high oxygen demand species. To explain further differences between both stream types in survival and recolonisation ability, 15 species traits were evaluated. These included so-called “ecological traits” (e.g., habitat and substrate range, density, distribution, current velocity adaptation) and “biological traits” connected with life cycle and larval/adult adaptations. Species showing the highest number of advantageous traits (with only exception of Electrogena sp. cf. ujhelyii — species of taxonomically unclear status) were able to successfully survive under the unfavourable conditions of the intermittent brook. Biological traits considered more important in many respects seem to be good predictors for assessing sensitivity to extreme temperature changes, hydrological regime fluctuations and the survival/recolonisation ability of species in exposed habitats.

scholarly journals Long-term changes of the ice regime of rivers in Latvia

2016 ◽  
Vol 47 (4) ◽  
pp. 782-798
Author(s):  
Inese Latkovska ◽  
Elga Apsīte ◽  
Didzis Elferts
Keyword(s):  
Regional Differences ◽  
Severity Index ◽  
Ice Cover ◽  
Ice Thickness ◽  
Positive Trend ◽  
The West ◽  
Climate Conditions ◽  
Long Term Changes ◽  
Ice Regime

The ice regime of rivers is considered a sensitive indicator of climate change. This paper summarises the results of research on the long-term changes in the ice regime parameters under changing climate conditions and their regional peculiarities in Latvia from 1945 to 2012. The ice cover duration on Latvian rivers has decreased during recent decades. The research results demonstrated that there is a positive trend as regards the formation of the ice cover and in 31.8% of the cases the trend is statistically significant at p < 0.05. As regards the breaking up of ice, there is a statistically significant negative trend in 93.2% of the cases at p < 0.05. This indicates an earlier ice break-up date, which in turn, displays a strong correlation with the increase of the air temperature. The same pattern applies to the reduction of the length of ice cover (a statistically significant trend in 86.4% of the cases at p < 0.05). In approximately 60% of the cases, there is a statistically significant reduction of the ice thickness. The estimated winter severity index indicates warmer winters over the last 20 years as well as regional differences in the west–east direction.

scholarly journals Fishery in the Tobol-Ishim interfluve in the neolithic and early metal age

2018 ◽  
Vol 7 (4) ◽  
pp. 182-192
Author(s):  
Viktor Alekseevich Zakh
Keyword(s):  
Water Level ◽  
Bronze Age ◽  
Iron Age ◽  
Life Support ◽  
Hydrological Regime ◽  
Economic Activities ◽  
Deep Foundation ◽  
Metal Age ◽  
North Western

Landscapes of the Tobol-Ishim interfluve were not stable in the Holocene and varied from forests and drowned floodplains at the beginning of the V and III millennia BC to steppificated territories with a lowered water level at the beginning of the Atlantic Period and in the middle of the Subboreal Period, which determined the main types of economic activities, one of them was fishing. Changes in hydrological regime of water bodies influenced the methods of fishing, including the use of different traps. Thus, in the Neolithic, when the water level decreased, the location of settlements in the system river-creek-lake (for example, Mergen 6), a large number of fish bones, bone harpoons, fishing spears, fishing tackles for catching pike and a total absence of plummets were indicative of individual fishing for large fish and, perhaps, of stop net fishery, which was facilitated by a decrease in the width of watercourses and tombolos. Stop net (stake net) fishery led to a settled lifestyle of the population, collective activities and the emergence of long-term settlements with deep foundation pits of dwellings. When the water level in rivers and lakes increased and floods became more frequent, the life support system changed, the population began to develop coasts more widely, its mobility increased, and they started to build framed above-ground dwellings. Following those changes, biconic, cigar-shaped, and corniculate plummets emerged in the Tobol River Basin and on the adjacent western and north-western territories in the III and early II millennium BC. When the water level was high, it was efficient to fish using traps, seines and, probably, nets, although the latter could also be used in drive hunting for shedding geese and ducks. Subrectangular plummets with one or two ties for fastening, and disk-shaped plummets with a tie in the center had been prevailing since the beginning of the II millennium BC; they existed until the first third of the I millennium BC. This period, the transition time from the Bronze Age to the Early Iron Age, is characterized by the absence of clay plummets, while there are large accumulations of fish scales and bones in the settlement layers. We can suppose that the population of that time (local Late Bronze Age population, mixed with northern migrants who made utensils with cross ornamentation) switched from net fishing to stop net fishing.

Impacts of national parks on tourism: a case study from a prominent alpine national park

2009 ◽  
pp. 103-120
Author(s):  
Michael Getzner
Keyword(s):  
Development Strategy ◽  
National Parks ◽  
National Park ◽  
Tourism Development ◽  
Positive Trend ◽  
The Difference ◽  
The Impact ◽  
Overnight Stays

-National parks and other categories of protected areas are often assumed to enhance regional economic development due to park tourism. The current study attempts to estimate the impact of the Hohe Tauern national park (Austria) on tourism by exploring whether and to what extent the national park may have had an influence on tourism development. For most national park communities, the results suggest that the establishment of the national park had some impact by enforcing an already positive trend or by weakening or reversing a negative trend of tourism. However, breakpoint tests exhibit turning points up to several years after the establishment of the park, indicating that taking a national park as the basis for tourism development is a medium to long term development strategy. In the short term, the impact of a national park on tourism is not measurable. Tourism increased by 1 to 3% annually after the breakpoint, indicating that the establishment of a national park has to be incorporated into the tourism and development strategy of a region right from the start. The causal relationship between the establishment of the national park and tourism development may be weak, in particular in communities where the difference between the actual and the forecast numbers of overnight stays is small. Marketing national park tourism and building up a brand or distinctive label may therefore contribute to regional development particularly in the long term.Key words: Tourism, national park, protected area, time series, stationarity, breakpoint test, ARIMA.JEL classifications: R110, L830, C220.Parole chiave: Turismo, parco nazionale, area protetta, serie temporale, stazionarietŕ, test di breakpoint, ARIMA.

The Impact of Climate Change on the Long-Term Response of Offshore Structures: A Study Case

2019 ◽  
Author(s):  
Irvin Alberto Mosquera ◽  
Luis Volnei Sudati Sagrilo ◽  
Paulo Maurício Videiro
Keyword(s):  
Climate Change ◽  
Global Climate ◽  
Global Climate Model ◽  
Offshore Structures ◽  
Global Climate Models ◽  
Wave Parameter ◽  
Greenhouse Emissions ◽  
The Impact ◽  
Term Response

Abstract This paper discusses the influence of the climate change in the long-term response of offshore structures. The case studied is a linear single-degree-of-freedom (SDOF) system under environmental load wave characterized by the JONSWAP spectrum. The wave parameter data used in the analyses were obtained from running the wind wave WaveWatch III with wind field input data derived from two Global Climate Models (GCMs): HadGEM2-ES and MRI-CGCM3 considering historical and future greenhouse emissions scenarios. The study was carried out for two locations: one in the North Atlantic and the other in Brazilian South East Coast. Environmental contours have been used to estimate the extreme long-term response. The results suggest that climate change would affect the structure response and its impact is highly depend on the structure location, the global climate model and the greenhouse emissions scenario selected.

scholarly journals Taking Students on a Journey to El Yunque

2016 ◽  
Vol 7 (1) ◽  
Author(s):  
Steven McGee ◽  
Jess K. Zimmerman
Keyword(s):  
Temporal Dynamics ◽  
Science Curriculum ◽  
Global Climate ◽  
Ecosystem Dynamics ◽  
Long Term Ecological Research ◽  
Hurricane Impact ◽  
The Individual ◽  
Long Term Impact ◽  
The Impact

As the developers of Journey to El Yunque, we have taken a different approach to the process of designing a science curriculum. Rather than start with a specific set of concepts or skills to target as learning outcomes, we started by identifying a specific community of practice to which we sought to connect students. Researchers in the El Yunque rainforest in Puerto Rico have been studying the impact of hurricanes on ecosystem dynamics and have been modeling what the long-term impact would be if changes to the global climate increase the frequency of severe hurricanes. Therefore, hurricane impact became the focal phenomenon for the unit. We modeled the process of investigating hurricane impact after the long-term ecological research practices of researchers in El Yunque. Students begin by investigating the long-term impact of hurricanes on the producers in El Yunque. Next students investigate the long-term impact of hurricanes on various consumers in the rainforest. Finally, students investigate how hurricanes impact the cycling of resources directly as well as indirectly through changes in organisms’ use of those resources in the rainforest. A central tension in the design process is how to coherently represent the spatial relationships between the components of the ecosystem and the temporal dynamics of the individual components. In this paper, we present the evolution of the program as we sought to balance that design tension and build an environment that connects students to the central phenomenon and practices of the community of researchers in El Yunque. 

scholarly journals Water Level Fluctuations in the Turawa Reservoir in Relation to the Tourist Use of the Water Body

2008 ◽  
Vol 13 (1) ◽  
pp. 133-144
Author(s):  
Andrzej T. Jankowski ◽  
Marek Ruman
Keyword(s):  
Water Level ◽  
Water Body ◽  
High Water ◽  
Ecological Condition ◽  
Water Levels ◽  
Water Level Fluctuations ◽  
Natural Factors ◽  
Odra River ◽  
The Impact ◽  
First Time

Abstract The aim of the paper is to assess the fluctuations of water levels in the Turawa Reservoir (50° 43’ N, 18° 08’ E) in relation to the tourist use of the water body. The reservoir is situated within the macroregion of the Silesian Lowland in the mesoregion of the Opole Plain. In administrative terms, the reservoir is situated in the pole Province within the borough of Turawa. In hydrological terms, in turn, it is situated in the catchment area of the Mała Panew river, which belongs to the basin of the Odra river. The Turawa Reservoir was opened for use in 1938, and in 1948 it was filled with water to its maximum for the first time. At present, the surface area of the reservoir, when it is filled with water to its maximum, is about 20.8 km2, its volume 99.5 mln m3, and its depth exceeds 13 meters. In the period of hydrological years 1976-2000 water levels in this reservoir were characterized by high, unnoticed in natural conditions, amplitudes of changes reaching 6.99 m. Anthropogenically stimulated fluctuations in the water level result in conflicts in terms of tasks and functions that the Turawa Reservoir was designed for. Changes in the level of the water surface in the Turawa Reservoir resulted from the impact of the natural factors (thaw and rainfall related high water levels), as well as anthropogenic ones (the need to improve sailing conditions, water supply for industrial and municipal needs). Decreasing the fluctuations of water levels in the Turawa Reservoir is necessary in order to maintain its tourist-recreational functions and keep the ecological condition of its waters at the appropriate level.

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